PO with sales tax - encumbrance balance not updating after line changed to tax exempt

Image 40 (production) & Image 48 (testing in progress)

PT 8.59 (production) & PT 8.60 (testing in progress)

Replication steps:

1. create PO for supplier flagged as sales tax applicable
2. Budget Check and Dispatch PO
3. Update PO line to Tax Exempt
4. Save, return to Main page, click Calculate, Save again
5. Change Order is created, but details are not listed in Change History, Line or Ship Changes
6. PO Total Amount is updated as expected but Encumbrance Balance is not updated.

Note: Upload Image option is not capturing the image.

Is there configuration required to trigger budget check when PO Line sales tax is updated?

Thank you,

Andrea Cameron